"Load-Sensitive Routing of Long-Lived IP Flows"
Anees Shaikh, Jennifer Rexford, and Kang G. Shin
Internet service providers face a daunting challenge in provisioning
network resources, due to the rapid growth of the Internet and wide
fluctuations in the underlying traffic patterns. The ability of
dynamic routing to circumvent congested links and improve application
performance makes it a valuable traffic engineering tool. However,
deployment of load-sensitive routing is hampered by the overheads
imposed by link-state update propagation, path selection, and
signalling. Under reasonable protocol and computational overheads,
traditional approaches to load-sensitive routing of IP traffic are
ineffective, and can introduce significant route flapping, since paths
are selected based on out-of-date link-state information. Although
stability is improved by performing load-sensitive routing at the flow
level, flapping still occurs, because most IP flows have a short
duration relative to the desired frequency of link-state updates. To
address the efficiency and stability challenges of load-sensitive
routing, we introduce a new hybrid approach that performs dynamic
routing of long-lived flows, while forwarding short-lived flows on
static preprovisioned paths. By relating the detection of long-lived
flows to the timescale of link-state update messages in the routing
protocol, route stability is considerably improved. Through
simulation experiments using a one-week ISP packet trace, we show that
our hybrid approach significantly outperforms traditional static and
dynamic routing schemes, by reacting to fluctuations in network load
without introducing route flapping.